make[2]: Entering directory '/tmp/ruby-2.4.4/ext/readline'
compiling readline.c
readline.c: In function ‘username_completion_proc_call’:
readline.c:79:42: error: ‘username_completion_function’ undeclared (first use in this function)
 # define rl_username_completion_function username_completion_function
                                          ^
readline.c:1869:37: note: in expansion of macro ‘rl_username_completion_function’
                                     rl_username_completion_function);
                                     ^
readline.c:79:42: note: each undeclared identifier is reported only once for each function it appears in
 # define rl_username_completion_function username_completion_function
                                          ^
readline.c:1869:37: note: in expansion of macro ‘rl_username_completion_function’
                                     rl_username_completion_function);
                                     ^
readline.c: At top level:
cc1: warning: unrecognized command line option ‘-Wno-self-assign’
cc1: warning: unrecognized command line option ‘-Wno-constant-logical-operand’
cc1: warning: unrecognized command line option ‘-Wno-parentheses-equality’
cc1: warning: unrecognized command line option ‘-Wno-tautological-compare’
Makefile:246: recipe for target 'readline.o' failed
make[2]: *** [readline.o] Error 1
make[2]: Leaving directory '/tmp/ruby-2.4.4/ext/readline'
exts.mk:248: recipe for target 'ext/readline/all' failed
make[1]: *** [ext/readline/all] Error 2
make[1]: Leaving directory '/tmp/ruby-2.4.4'
uncommon.mk:220: recipe for target 'build-ext' failed
make: *** [build-ext] Error 2